ZyXEL Communications PLA-470 V2 - V3.0.5 Installationsanleitung PDF herunterladen (Seite 170)

CHAPTER 8

Installation

The disturbances received and caused by PLC networks must be taken into account

when installing the network. The electrical topology of the building or buildings

where the devices will be installed is also a major element to be considered for build-

ing the architecture of the PLC network.

Therefore, the definition of the electrical network topology is an essential step.

It determines the PLC network data transmission performance. PLC devices,

whether mobile or fixed on the electrical network, provide various data link quali-

ties depending on their position, the presence of disturbing electrical devices nearby,

and the filters installed to protect the electrical network from spurious frequency

injections.

Another constraint relates to the actual bit rates since the claimed rates never

correspond to what is available to the user. An unexpected lower bit rate generally

originates from some mechanisms offered by PLCs. However, this lower bit rate can

be minimized by choosing suitable mechanisms and associated parameters when

configuring PLC devices and, more especially, the PLC gateway or the central

device.

As far as security is concerned, we can see that it is important to implement suit-

able techniques for data encryption and the separation of logical networks on the

electrical network, which can be viewed as a shared data bus. Since the PLC signal’s

propagation goes via the electrical meters for domestic, professional, or industrial

facilities, it is important to use passwords for the PLC local area network that pro-

tect data exchanges.

The modeling of an electrical network is difficult and the performance can

quickly vary according to the use of PLC devices. This chapter gathers useful infor-

mation on understanding these variations and improving performance.

Frequency Bands

General public and professional PLCs use two frequency bands: the 3- to 148-kHz

frequency band for low rate technologies and the 1- to 30-MHz frequency band for

high rate technologies.

PLC technologies for MV (medium voltage) electrical networks, also called BPL

(broadband powerLine), may use the 30- to 50-MHz frequency band. These tech-

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ZyXEL Communications PLA-470 V2 - V3.0.5 Installationsanleitung Seite 170